Is the Gearbox Dead?

Julia Munday

Thursday 29th September 2011

By 2009 the relatively cheap synchronous permanent magnet gearless machines that had been originally developed for MRL applications were being applied more widely, with many manufacturers offering packages consisting of machines, bedplates and divertor pulleys aimed at the modernisation market and many consultants specifying these systems for low to medium rise buildings because of their perceived benefits with regard to reduced running costs and general eco-friendliness as exemplified by environmental assessment methods such as BREEAM made it a good time to carry out an objective study comparing the capital and running costs of schemes using a traditional geared machine with schemes using a gearless machine for a range of real life modernisation applications. The Perceived Benefits of PM Gearless Machines. The main points are as follows: -They are more efficient and can be used with regenerative drives, thus saving energy; -One machine model can be applied to a larger range of applications than a geared machine thus making it more economical to hold stocks “on the shelf” reducing lead times; -Cleaner than a geared machine because no oil reservoir is required; -Machines are designed to be low maintenance and should offer savings on long term maintenance costs. Possible Disadvantages of PM Gearless Machines. The main points are as follows: -Most machines are designed for use with new MRL package lifts, i.e. lightweight lift cars and multi-reeved pulleys (2:1 systems being common with 4:1 and even 6:1 systems used for larger capacity lifts) whereas a traditional lift will have heavier cars and 1:1 roping; -Many packages designed for modernisation use rope diameters and pulley diameters smaller than permitted by EN81-1 to convert existing 1:1 roped systems to multi-reeved systems; -The machines may need “exotic” arrangements of divertor pulleys to increase the angle of wrap of the ropes on the sheave to achieve traction

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